Composites have been employed in the construction of all types of useful articles such as, storage vessels, transportation containers, vehicle parts including cars, trucks, boats and airplanes and the like. These objects, as with all objects, are subject to damage through use. In many instances, these damages will occur at places remote from adequate repair facilities and it is desirable to have means for expedient and often temporary but structurally sound repairs. One method for repairing these composite articles is to adhere, via adhesive bonding, precured composite or metal repair patches to the damaged area(s). Another method is to remove the damaged part and rebuild the part under heat and vacuum in the same manner as the original part was manufactured.
Since these composite objects are employed, for the most part outdoors, they are subjected to all types of environments. In humid environments, the composites tend to absorb moisture. The moisture in wet composites tends to vaporize when subjected to the heat usually involved in curing the patches during their repair, and causes blistering, disbondment and often delamination. It would be desirable to have available an adhesive and or a resinous binder material for use in the repair of the objects prepared from composites which cure below the normal curing temperature of the epoxy resins currently employed in the repair of composite parts or objects. The repair material would most preferably cure below the boiling point of water and produce a polymeric system which has thermal and mechanical properties similar to the composite part being repaired. One method to accomplish this is to have available such adhesive or binder resins which are low temperature curable but yet have sufficient thermal properties, cured strength and water resistance so as to be suitable for use in the repair of the damaged composites.
Low temperature curable epoxy resin systems with good thermal and mechanical properties would also find use in many other applications. Other applications for these resin systems would include uses such as electronic encapsulants, production of electrical laminates, and structural composite parts. The ability to cure epoxy resins at relatively low temperatures would make these materials especially valuable in several composite production techniques like resin transfer molding, braiding, filament winding, pultrusion and similar methods of rapid composite formation.